In Standard Billing Process (in VF01 Transaction), there is a Billing Date in Header Tab which is in Editable Mode. Now, sometimes user change this date. One more condition is that the Actual GI Date in Delivery and Billing Date must be equal.
So I want that Billing Date Field should be in NON-EDITABLE mode. So please provide the solution.
if it is not possible to disable the field why dont you try to raise as error if the values of the two dates are different, you would need to find the right enhancement where you have both dates avaliable.
You can check BADI: SD_CIN_LV60AU02 for starters searching the SCN would definitely help you in finding the correct enhancement and if you are in ECC6 you can try to implement some enhancement point for it also.